In the related art, a technology is disclosed in which a foot portion of a user is detected by a radio wave sensor for the opening and closing of a vehicle door, which is provided in a lower portion of a vehicle, and the vehicle door is opened or closed upon the detection of the foot portion (refer to JP2005-133529A (Reference 1)). In the technology disclosed in Reference 1, the detecting sensor is provided in a concave portion formed in a rear bumper or a side sill cover, so as to face the ground, and when the detecting sensor detects the foot portion of the user, a corresponding vehicle door is automatically opened.
In the technology disclosed in Reference 1, the user is required to approach the vehicle, almost coming into contact with the vehicle, in such a manner that the detecting sensor for the opening of a vehicle door operates. After the user approaches the vehicle, almost coming into contact with the vehicle so as to active the detecting sensor, the user is required to immediately and sufficiently separate from the vehicle so that the user can avoid collision with the automatically opening vehicle door. When the user holds large luggage in the hands, it is difficult for the user to sufficiently approach the vehicle so as to operate the detecting sensor. As such, the technology of the related art has the problem related to user-friendliness or the safety of the user.